Device and method for operating a refrigeration cycle without evaporator icing

ABSTRACT

The present invention relates to a device and method for operating a refrigeration cycle without icing of the evaporative surface of the device.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part of application Ser.No. 10/213,347, filed Aug. 5, 2003, which is a continuation-in-part ofapplication Ser. No. 09/859,829, filed May 16, 2001, issued to Alan W.Bagley, which applications are both incorporated by reference as iffully set forth, including the drawings, herein.

FIELD OF THE INVENTION

[0002] The present invention relates to a device and method forpreventing ice formation on the evaporator of a device operating in arefrigeration cycle.

BACKGROUND OF THE INVENTION

[0003] The refrigeration cycle has numerous uses. One, of course, isrefrigeration, the cooling of ambient air in an enclosure to atemperature at or below freezing for the purpose of preventing thespoilage of comestibles such as meat, fresh fruit and fresh produce.Another is building air conditioning. A further use for therefrigeration cycle is removing water from moist air. The purpose maysimply be to dry the air as in the case of household dehumidifiers,industrial scale fruit and vegetable dryers and the like. Or the purposemay be to produce potable water for personal household use, camping,public water conservation and the like or for use during emergenciessuch as earthquakes, floods, fire and other natural disasters orman-made disasters such as war, when the normal water supply iscompromised. In any event, the device and method employed is essentiallythe same and is schematically depicted in FIG. 1.

[0004] In FIG. 1, compressor 1 receives a refrigerant gas, such asammonia, sulfur dioxide, Freon®, and the like, and compresses it, i.e.,raises its pressure. As the result of being compressed, the gas heatsup, becoming a hot, high pressure, gas. The hot, high pressure gas isthen received by condenser 2, which consists of a heat exchanger havinga large surface area that is in contact with circulating ambient air.

[0005] The hot, high pressure gas surrenders some of its heat content tothe circulating air and, as a result, is condensed to a liquid which,while still warm, is cooler than the hot gas entering the condenser. Thewarm, high pressure liquid then travels to metering device 3, which canbe a simple orifice, a capillary tube or a thermostatic expansion valve,and which forces the liquid to expand and thereby cool further. The coolliquid then travels to evaporator 4, which, like the condenser, consistsof a large surface area over which moisture-containing air can becirculated. The evaporator can be merely a length of tubing that hasbeen folded over on itself in a serpentine manner as depicted in FIG. 1.Or the tubing can be flattened to provide more surface area when it isfolded into a given volume of space. The tubing may also have vanesattached to provide more surface area. The evaporator can also be aninterconnected hollow core honeycomb such as the radiator of anautomobile. These and many other evaporator designs are well-known inthe art. In any event, the cool liquid passing through evaporator 4absorbs heat from the air in contact with the exterior surface of theevaporator and, when enough heat energy, called the heat ofvaporization, has been absorbed, converts back into a gas, which is atapproximately the same temperature as the cool liquid entering theevaporator, the heat absorbed having been used in the vaporizationprocess. When the device is being used as a dehumidifier, the operatingparameter of metering device 3 is such that the temperature of the cool,low pressure liquid circulating through the evaporator 4 is below thedew point of the air in contact with the exterior surface of theevaporator. The dew point is the temperature at which water vapor in airwill condense. Thus, as the cool liquid circulates through theevaporator; absorbs heat from the surrounding air through the surface ofthe evaporator and vaporizes, water vapor-containing air in contact withthe evaporator is cooled to below its dew point. Water vapor in the airthen condenses on the evaporator and flows out of the system. The coolgas returns to the compressor to begin another cycle. A receiver issometimes placed in the system between the condenser and the meteringdevice to store the warm, high pressure, refrigerant liquid until it iscalled for by the metering device.

[0006] When the purpose of the device shown in FIG. 1 is merely to cooland/or dry air, the water condensing on the evaporator is allowed tosimply drain away. When the purpose is to collect potable water, areservoir is placed beneath the evaporator. Care must be taken to assurethat the water is obtained in potable condition and that it remains soafter collection. This is accomplished by manufacturing the evaporator,the reservoir and any other parts of the device that come in contactwith the moist air or the condensed water, from non-contaminatingmaterials or to coat or line potentially contaminating materials withthe non-contaminating kind. Examples of such materials are stainlesssteel, glass and a broad range of polymeric materials such as PVC,Teflon® and the like. To ensure that collected water remains potable,such procedures as irradiating the water with ultraviolet light,bubbling ozone through it, adding iodine or other chemicalanti-microbial agents, etc., are often used.

[0007] The device described above works reasonably well at ambient airtemperatures above about 55° F. A problem arises, however, when the airtemperature is below about 55° F. such as might be encountered inrefrigeration units, fruit and vegetable produce drying rooms and meatstorage lockers or when potable water is needed and the ambienttemperature is less than about 55° F., such as at night or in winter.The problem is that, as water vapor, which is at about 55° F. or below,is condensed on the evaporator surface of the device in FIG. 1, it israpidly cooled further because the evaporator surface is usually at atemperature substantially below 32° F. due to the thermodynamiccharacteristics of commonly used refrigerants and the normal operatingmodes of such devices. At 32° F. or below, the condensate freezes,forming ice on the evaporator. At ambient air temperatures below about55° F., air that is in contact with the water on the surface of theevaporator cannot supply sufficient additional heat to counteract thisfreezing condition. As a result, ice builds up on the evaporator surfaceand acts as an insulator, isolating the evaporator surface from themoisture-laden air and thereby interfering with the operation of thedevice. When this occurs, the usual remedy is to turn off thecompressor, shutting down the device, until the ice melts. The result isthat the device of FIG. 1 is extremely inefficient at ambient airtemperatures below about 55° F.

[0008] One approach that is employed to avoid evaporator icing is tosimply run the device at higher refrigerant temperatures. This, however,limits the cooling capability of the device. Furthermore, if the goal isto remove water from the ambient air, it is preferred that the device berun as cold as possible so that the air is cooled to as close to thefreezing point of water as possible since the colder the air, the lesswater it can retain. Running the device at a higher refrigeranttemperature is thus inefficient since it leaves water in the air.

[0009] An approach employed to reduce inefficiency due to down time isto use multiple devices and to alternate use so that when the evaporatorof one device has iced up, it can be shut down and another devicestarted up. This, however, is an expensive, not to mentionspace-consuming, resolution.

[0010] What is needed is a device and method that performs arefrigeration cycle, in particular at temperatures below about 55° F.,without evaporator icing. The present invention, provides such a device.

SUMMARY OF THE INVENTION

[0011] The invention includes a device that permits the operation of arefrigeration cycle while avoiding evaporator icing, including but notlimited to air conditioners, dehumidifiers, water makers, and bothcommercial and consumer refridgerators and freezers. The devicecomprises a compressor comprising an inlet and an outlet; a condenser,comprising an inlet and an outlet, wherein the condenser inlet isoperatively coupled to the outlet of the compressor; a metering means,comprising an inlet and an outlet, wherein the inlet of the meteringmeans is operatively coupled to the outlet of the condenser; anevaporator, comprising an inlet, an outlet and an evaporative surface,wherein the evaporator inlet is operatively coupled to the outlet of themetering means and the outlet of the evaporator is operatively coupledto the inlet of the compressor; a hot gas bypass means, comprising aninlet, an outlet, an open position and a closed position, wherein thehot gas bypass means inlet is operatively coupled to the outlet of thecompressor and the hot gas bypass means outlet is operatively coupled tothe inlet of the evaporator or to an inlet of a manifold, wherein:

[0012] the manifold comprises an inlet and a plurality of outlets, eachoutlet being operatively coupled to a different one of a plurality ofinlets at different locations on the evaporative surface; the hot gasbypass means also being operatively coupled to a controller; acontroller for actuating the hot gas by-pass means; and, a refrigerantthat circulates from the compressor to the condenser to the meteringmeans to the evaporator and back to the compressor in a refrigerationcycle. The controller actuates the hot gas bypass means in response to asignal. The signal may originate from any number of possible devicesincluding but not limited to one or more of a timer, a temperaturesensot or temperature sensing means, or a device capable of detectingice formation. In embodimetns including a timer, the timer may beincorporatted in the controller. In embodimetns including one or moremeans for detecting the initiation of ice formation on the evaporativesurface, each means is operatively coupled to the evaporative surfacewherein if there is more that one, each is operatively coupled to adifferent location on the evaporative surface, and to the controller.The means for detecting the formation of ice may include optical meansfor detecting the formation of ice.

[0013] In an aspect of this invention, the means for detecting theformation of ice on the evaporative surface comprise(s) one or morelasers.

[0014] In an aspect of this invention, the means for detecting theformation of ice on the evaporative surface comprise(s) one or morefrost detectors.

[0015] In an aspect of this invention, the means for detecting theformation of ice on the evaporative surface comprise(s) one or morefirst temperature sensing means coupled to one or more work-loadtemperature sensitive sub-assembly(ies) of the device.

[0016] An aspect of this invention is any of the above devices whichfurther comprises one or more second temperature sensing means coupledto the evaporative surface, wherein if there is more than one, each iscoupled to a different location on the evaporative surface, and to thecontroller.

[0017] An aspect of this invention is the above device in which themeans for detecting the formation of ice on the evaporative surfacecomprises one or more third temperature sensing means coupled to theevaporative surface wherein, if there is more than one, each is coupledto a different location on the evaporative surface.

[0018] The metering means comprises a thermostatic expansion valve inany of the above devices.

[0019] In the device comprising the third temperature-sensing means, thethermostatic expansion valve further comprises a temperature-sensingassembly in another aspect of this invention.

[0020] In an aspect of this invention, the temperature-sensing assemblycomprises a double-walled container comprising an inner member and anouter member; a first space disposed between the inner member and theouter member; a second inner space circumscribed by the inner member; aninlet disposed proximate to, in and through a first end of the outermember, the inlet being operatively coupled to the outlet of theevaporator; an outlet disposed proximate to, in and through a second endopposite the first end of the outer member, the outlet being operativelycoupled to the inlet of the compressor; a baffle disposed in the firstspace and extending from proximate to the first end of the outer memberto proximate to the second end of the outer member; a temperaturesensing bulb disposed in the inner space, the temperature sensing bulbbeing operatively coupled to the thermostatic expansion valve; and, athermal compound also disposed in the inner space, the thermal compoundbeing in contact with the inner member and the temperature-sensing bulb.

[0021] In any of the above devices, the hot gas by-pass means comprisesa valve in an aspect of this invention.

[0022] The valve comprises a solenoid in an aspect of this invention.

[0023] An aspect of this invention is that, in any one of the abovedevices, each temperature-sensing means independently comprises athermocouple or a thermistor.

[0024] The controller comprises a microprocessor in any of the abovedevices in an aspect of this invention.

[0025] An aspect of this invention is a method for performing arefrigeration cycle without ice build-up on the evaporative surface,comprising providing a compressor comprising an inlet and an outlet;providing a condenser, comprising an inlet and an outlet, wherein thecondenser inlet is operatively coupled to the outlet of the compressor;providing a metering means, comprising an inlet and an outlet, whereinthe inlet of the metering means is operatively coupled to the outlet ofthe condenser; providing an evaporator, comprising an inlet, an outletand an evaporative surface, wherein the evaporator inlet is operativelycoupled to the outlet of the metering means and the outlet of theevaporator is operatively coupled to the inlet of the compressor;providing a hot gas bypass means, comprising an inlet, an outlet, anopen position and a closed position, wherein the hot gas bypass meansinlet is operatively coupled to the outlet of the compressor and the hotgas bypass means outlet is operatively coupled to the inlet of theevaporator or to an inlet of a manifold, wherein:

[0026] the manifold comprises an inlet and a plurality of outlets, eachoutlet being operatively coupled to a different one of a plurality ofinlets at different locations on the evaporative surface;

[0027] the hot gas bypass means also being operatively coupled to acontroller; providing one or more means for detecting ice formation onthe evaporative surface, each such means being operatively coupled tothe evaporative surface wherein, if there is more than one means, eachis coupled to a different location on the evaporative surface, and tothe controller; providing one or more temperature sensing means coupledto the evaporative surface and operatively coupled to the controller;providing a controller operatively coupled to each means for detectingthe formation of ice on the evaporative surface, to each temperaturesensing means and to the hot gas by-pass means; and, providing arefrigerant that circulates from the compressor to the condenser to themetering means to the evaporator and back to the compressor in arefrigeration cycle; wherein:

[0028] when the means for detecting ice formation on the evaporativesurface detect(s) such ice formation, a signal is sent to the controllerwhich in turn sends an open signal to the hot gas bypass means, the hotgas bypass means remaining open until the controller receives a signalfrom the temperature sensing means that is above a pre-set value, atwhich time the controller sends a close signal to the hot gas bypassmeans.

[0029] In the above method, the means for detecting the formation of iceon the evaporative surface comprise(s) one or more lasers in an aspectof this invention.

[0030] In the above method the means for detecting the formation of iceon the evaporative surface comprise(s) one or more frost detectors inanother aspect of this invention.

[0031] In the above method, the means for detecting the formation of iceon the evaporative surface comprise(s) one or more first temperaturesensing means coupled to one or more work-load temperature sensitivesub-assembly(ies) of the device in a further aspect of this invention.

[0032] In the above method, each temperature sensing means comprises athermocouple or a thermistor in an aspect of this invention.

[0033] In the above method the metering means comprises a thermostaticexpansion valve in an aspect of this invention.

[0034] In the above method, the hot gas by-pass means comprises a valvein an aspect of this invention.

[0035] In the above method, the valve comprises a solenoid in an aspectof this invention.

[0036] In the above methods, the controller comprises a microprocessorin an aspect of this invention.

[0037] An aspect of this invention is a method for performing arefrigeration cycle without ice build-up on the evaporative surface,comprising providing a compressor comprising an inlet and an outlet;providing a condenser, comprising an inlet and an outlet, wherein thecondenser inlet is operatively coupled to the outlet of the compressor;providing a metering means, comprising an inlet and an outlet, whereinthe inlet of the metering means is operatively coupled to the outlet ofthe condenser; providing an evaporator, comprising an inlet, an outletand an evaporative surface, wherein the evaporator inlet is operativelycoupled to the outlet of the metering means and the outlet of theevaporator is operatively coupled to the inlet of the compressor;providing a hot gas bypass means, comprising an inlet, an outlet, anopen position and a closed position, wherein the hot gas bypass meansinlet is operatively coupled to the outlet of the compressor and the hotgas bypass means outlet is operatively coupled to the inlet of theevaporator or to an inlet of a manifold, wherein:

[0038] the manifold comprises an inlet and a plurality of outlets, eachoutlet being operatively coupled to a different one of a plurality ofinlets at different locations on the evaporative surface;

[0039] the hot gas bypass means also being operatively coupled to acontroller; providing one or more temperature sensing means coupled tothe evaporative surface, wherein if there is more than one, each iscoupled to a different location on the evaporative surface; providing acontroller operatively coupled to each temperature sensing means and tothe controller; wherein:

[0040] each temperature-sensing means measures a temperature at itslocation on the evaporative surface and sends a signal corresponding tothat temperature to the controller wherein, if the signal is at or belowa pre-selected first set point temperature, the controller sends an opensignal to the hot gas bypass means, the hot gas bypass means remainingopen until the controller receives a signal from the temperature-sensingmeans than is above a pre-selected second set point temperature, atwhich time the controller sends a close signal to the hot gas bypassmeans.

[0041] In the above method, the metering means comprises a thermostaticexpansion valve in an aspect of this invention.

[0042] In the above method, the thermostatic expansion valve furthercomprises a temperature-sensing assembly.

[0043] The temperature-sensing assembly comprises a double-walledcontainer comprising an inner member and an outer member; a first spacedisposed between the inner member and the outer member; a second innerspace circumscribed by the inner member; an inlet disposed proximate to,in and through a first end of the outer member, the inlet beingoperatively coupled to the outlet of the evaporator; an outlet disposedproximate to, in and through a second end opposite the first end of theouter member, the outlet being operatively coupled to the inlet of thecompressor; a baffle disposed in the first space and extending fromproximate to the first end of the outer member to proximate to thesecond end of the outer member; a temperature sensing bulb disposed inthe inner space, the temperature sensing bulb being operatively coupledto the thermostatic expansion valve; and, a thermal compound alsodisposed in the inner space, the thermal compound being in contact withthe inner member and the temperature-sensing bulb, in another aspect ofthis invention.

[0044] In the above methods, the hot gas by-pass means comprises a valvein an aspect of this invention. In the above method the valve comprisesa solenoid in an aspect of this invention. In the above methods, eachtemperature-sensing means independently comprises a thermocouple or athermistor in an aspect of this invention, and in the above methods, thecontroller may comprise a microprocessor in an aspect of this invention.

[0045] In one aspect of the invention the method further includesproviding a signal source communicating with the controller. The signalsource may include one or more of timer, a temperature sensing means,and/or an ice detection means. In some embodiments the method includesate least two such signal sources. In embodiments with only one signalsource, the signal source may be used to alternately activate anddeactivate the hot gas bypass means. For example, an embodimentincluding a timer may us the timer to alternately signal the controllerto activate and deactivate the hot gas bypass means. In methods of theinvention including more than one signal source, each signal source maybe responsible for causing the controller to act. For example, onemethod of the invention may include the step of causing a signal fromone or more of a timer means, a temperature sensing means, and a icedetection means to be received by the controller, causing the controllerto activate the hot gas bypass. And, further include the step of causinga signal from one or more of a timer, a temperature sensing means,and/or an ice detection means to be received by the controller, causingthe controller to deactivate the hot gas bypass. In some embodiments,one signal source is responsible only for causing the controller toactivate the hot bypass means, and another signal source is responsibleonly for causing the controller to deactivate the hot gas bypass mean.In other methods of the invention, the signal sources may be used foreither purpose.

DETAILED DESCRIPTION OF THE INVENTION

[0046] Brief Description of the Figures:

[0047] Figures are provided solely to aid the reader in understandingthe invention. They are not intended and are not to be construed aslimiting the scope of this invention in any manner whatsoever.

[0048]FIG. 1 is a schematic representation of a prior art refrigerationcycle device.

[0049]FIG. 2 is a schematic representation of a refrigeration cycledevice of this invention using a capillary metering means and a hot gasbypass.

[0050]FIG. 3 is a schematic representation of a refrigeration cycledevice of this invention using a TXV metering means and a hot gasbypass.

[0051]FIG. 4 is a schematic representation of a temperature-sensingassembly of this invention.

[0052]FIG. 5 is a schematic representation of a portion of a device ofthis invention, that portion being a plurality of ice formationdetectors on the evaporative surface, a manifold hot gas bypass systemand the controller that integrates the two to prevent the buildup of iceon the evaporative surface.

[0053]FIG. 6 is a schematic representation of a refrigeration cycledevice of freezer embodiment of the invention showing several examplesignal sources in communication with the controller.

DEFINITIONS

[0054] A timer or timer means as used herein shall mean any knownapparatus or method for timing events including but not limited to atiming circuit integral with the controller, such as timing circuit in amicroprocessor used as the controller.

[0055] As used herein, a “refrigerant” or a “refrigerant gas” relates toa fluid that, in its liquid form has a boiling point below that ofwater. Examples, without limitation, of refrigerants are ammonia, sulfurdioxide and Freon®.

[0056] As used herein, a “compressor” refers to any device that iscapable of pressurizing a fluid, including liquids and gases. In thepresent invention, the compressor is capable in particular ofpressurizing a gas. Many such devices are well-known in the art and anysuch device is within the scope of this invention.

[0057] As used herein, a “condenser” refers to any device that iscapable of receiving compressed or pressurized gas from a compressor,releasing heat energy from the compressed gas and converting it to aliquid while essentially maintaining the pressure established by thecompressor. Such devices are likewise well-known in the art and any suchdevice is within the scope of this invention.

[0058] As used herein, a “metering means” or “metering device” bothrefer to any device that is capable of receiving a liquid at a firstpressure at its inlet and expelling that liquid at a second, reducedpressure at its outlet. Such devices include, without limitation, asimple orifice, an orifices containing a floating piston, a flowrestrictor, a capillary tube and a thermostatic expansion valve (TXV).These and other such devices are well-known in the art and all arewithin the scope of this invention.

[0059] As used herein, an “evaporator” or an “evaporator assembly” bothrefer equally to any device, which has a large exterior surface area,called herein, the “evaporative surface,” over which air containingwater vapor may circulate with the result that, when the temperature ofa liquid within the evaporator is below the dew point of the air flowingover it, water vapor in the air will condense on the exterior surface ofthe evaporator and gravitationally flow off of it while, at the sametime, the liquid in the evaporator vaporized to a gas.

[0060] As used herein, “hot gas bypass,” “hot gas bypass means” or “hotgas bypass device” all refer to a device which is capable ofcontrollably delivering a hot fluid from a first location to a secondlocation where there is a cool fluid in such a manner that the twofluids mix, while bypassing other devices disposed in a different paththat also connects the first location with the second location. A“fluid” may refer to a gas or a liquid. With regard to a hot gas bypass,an “open signal” refers to a signal that, when received by the hot gasbypass, causes the hot gas bypass to open and allow the hot fluid toflow and mix with the cool fluid. Conversely, a “close signal” is asignal that, when received by the hot gas bypass, causes the hot gasbypass to close thereby discontinuing the mixing of flow of hot gas withthe cool liquid.

[0061] By “controllably delivering” is meant that the device is capableof opening and closing such that only that amount of hot fluid isdelivered to and mixed with cool fluid as is required to maintain aselected temperature in the fluid resulting from the mixing of the hotand the cool fluids.

[0062] As used herein, a “refrigeration cycle” refers to the well-knownthermodynamic cycle of gas compression to a hot, high pressure gas,condensation of the hot, high pressure gas to a warm, high pressure gaswith concomitant release of heat energy to the external surroundings,metering of the warm, high pressure gas through a device permittingexpansion of the liquid to afford a cool, low pressure liquid,evaporation of the cool, low pressure liquid to a cool, low pressure gaswith concomitant absorption of heat energy from the externalsurroundings and re-compression of the cool, low pressure gas to beginthe cycle again. In one sense, the refrigeration cycle is considered tobe a cooling means. However, if air in contact with the outside of theevaporator contains water vapor and the temperature of the cool liquidin the evaporator is below the dew point of the air, then water willcondense on the outside of the evaporator resulting in its removal fromthe air. Thus, the refrigeration cycle may be considered a water-removalmeans as well as a cooling means. With regard to the terms “hot,” “warm”and “cool,” when referring to the refrigerant liquid/gas used in thedevice herein, it is to be recognized that these terms are being usedstrictly in their comparative sense, that is, “hot” is a highertemperature than “warm,” which is a higher temperature than “cool.” Itis unnecessary to the understanding or operation of the device andmethod of this invention to speak in terms of absolute temperatures ortemperature ranges, except where expressly set forth, because these willdepend on the refrigerant used, the degree of pressurization of therefrigerant in the compressor, the amount of heat that must be removedfrom the hot, high pressure gas in the condenser to obtain a liquid,etc. and each of these is readily determinable by those skilled in theart using standard thermodynamic principles.

[0063] As used herein, a “temperature sensing means” refers to a devicethat is capable of measuring temperature at a specific location andincludes, without limitation, a thermometer, a thermocouple, athermister and the like.

[0064] As used herein, a “controller” refers to a device that is capableof causing an event based on a received signal. For example, acontroller upon receiving the appropriate signal from one or more of atimer, a temperature sensing means, or an ice detecting means, iscapable of causing the hot gas bypass to open or close and therebypermit or prohibit the mixing of hot gas and cool liquid. A controllermay comprise mechanical, electrical or optical components ofcombinations thereof. In a presently preferred embodiment of thisinvention, a controller comprises a microprocessor. In some embodimetns,the controller may incorporate the signal source. For example thecontroler could be a microprocessor with an integral timer.

[0065] A “thermostatic expansion valve” or “TXV” refers to thewell-known in the refrigeration art device commonly used inrefrigeration systems for causing the expansion of the warm, highpressure liquid coming from the condenser of such a system to a cool,low pressure liquid.

[0066] As used herein, a “temperature-sensing gas bulb” refers to thewell-known in the refrigeration art device that controls the amount ofhigh pressure warm liquid that is expanded in a TXV at a given time,

[0067] As used herein, a “temperature-sensing assembly” refers to atemperature-sensing gas bulb in combination with a double-walledcontainer and a thermal compound as described elsewhere herein.

[0068] A “thermal compound” refers to a material that isthermoconductive and can transfer temperatures detected in one region ofa volume of the material quickly and accurately to another region of avolume of the material.

[0069] As used herein, a “double walled container” refers to a containerthat has an inner and an outer wall and a space between them. Anexample, without limitation, of a double-walled container is a commonThermos®. In fact, a Thermos®, modified in a manner that will be clearto those skilled in the art based on the disclosures herein, wouldcomprise a “double-walled container” of this invention.

[0070] As used herein, a space “circumscribed” by a member refers simplyto a volume within a container such as, without limitation, the volumein a can, a cup, a Thermos® or a bottle wherein the volume is uniquelydetermined and confined by the inner surface of the can, cup, Thermos®or bottle.

[0071] As used herein, a “baffle” refers to a partial obstruction placedin the flow path of a fluid in a conduit such that, to continue flowing,the fluid must negotiate around the partial obstruction such that theeffective length of the path of the fluid through the baffled area isgreater than it would have been in the absence of the baffle and, thus,the residence time of the fluid in that part of the conduit is longer.

[0072] As used herein, a “hot gas bypass valve” refers to any manner ofvalve that can be placed in a conduit in such a manner that opening andclosing the valve permits or prohibits the flow of a fluid through theconduit. Examples, without limitation, of hot gas bypass valves would beneedle valves, stop-cock valves and internal piston solenoid valves andzero-differential solenoid valves.

[0073] A “solenoid” refers to the well-known control device whereinelectromagnetic force is used to move a plunger, the movement of whichcan cause another device or another portion of a device containing asolenoid to start or stop, open or shut, etc.

[0074] Ozone is a triatomic version of oxygen; i.e., O₃.

[0075] An “ozone generator” refers to a device that produces ozone fromoxygen. Common types of ozone generators are a corona dischargegenerator, a cylindrical dielectric generator, an electrostaticgenerator and a Siemens-type generator. Any of these ozone generatorsmay be used with the device of this invention. However, in a presentlypreferred embodiment of this invention, an electrostatic ozone generatoris used.

[0076] “Fritted glass” refers to beads or fibers of glass that have beenfused together at a temperature that forms a relatively strong glassobject such as, without limitation, a disk, a solid glass tube, a mat,etc., but that is sufficiently porous to permit gases to dispersethrough in bubble sizes dependent on the size of the pores. As usedherein “fritted glass dispersion device” is a device which is placed ina water collection reservoir placed under an evaporator and which isconnected to an ozone generator such that ozone from the generator flowsthrough and is dispersed in small bubbles into water in the collectionreservoir.

[0077] A “thermocouple” is a device consisting of two dissimilar metalsjoined such that a potential difference is generated between the pointsof contact is a measure of the temperature difference between thepoints.

[0078] The “dew point” is the temperature to which air must be cooled atconstant pressure and water vapor content in order to reach saturation.A state of saturation exists air is holding the maximum amount of watervapor possible at a given temperature and pressure without the watervapor condensing to liquid water. At temperatures below the dew point,water vapor in the air precipitates as liquid water.

[0079] A “microprocessor” refers to an integrated circuit containing thearithmetic, logic and control circuitry required to interpret andexecute instructions from a computer program.

[0080] As used herein, the term “about” refers to ±5% of any valuegiven.

Discussion

[0081]FIG. 1, which schematically depicts a prior art standardrefrigeration cycle device, is described in the Background section.

[0082] The present invention relates to a device that operates in arefrigeration cycle while avoiding ice formation on its evaporativesurface. While the device will operate without icing at virtually anytemperature, it is particularly useful at low ambient temperatures;i.e., temperatures below about 55° F. and even at temperatures at orbelow freezing (below 32° F.). It is at the lower ambient airtemperatures that icing is particularly problematic and the deviceherein is of the greatest utility. By “ambient air temperature” is meantthe temperature of atmospheric air external to and in the environswherein the device is located.

[0083] A presently preferred embodiment of this invention is a devicefor avoiding evaporator icing at ambient air temperatures from anytemperature up to about 55° F.

[0084] To accomplish the above, a device of this invention comprises ahot gas bypass that permits the output of a compressor, i.e., hot, highpressure gas, to be mixed with the output of a metering means, i.e.,cool, low pressure liquid, in a controlled manner, at a locationproximate to the output of the metering means. Examples of usefulmetering means are a simple orifice, an orifice with a floating piston,a capillary tube or a thermostatic expansion valve (TXV). The hot gasbypass is in communication with a controller. The controller is also incommunication with one or more signal sources such as timers, icedetectors, or temperature sensors. In Embodimetns using temperaturesensors, some sensors may be placed proximate to the inlet of theevaporator or at various locations on the evaporative surface. Thetemperature sensors measure the temperature of the low pressure liquidentering the evaporator, if the sensor is located proximate to the inletto the evaporator, or the temperature of the evaporative surfacewherever on the surface the sensor is placed, and provides a signalcorresponding to that temperature to the controller. In this embodiment,the controller comprises a low temperature set point and a hightemperature set point. When the temperature sensor sends a temperaturesignal to the controller that is at or below the low temperature setpoint, the controller causes the hot gas bypass to open, permitting hotgas from the outlet of the compressor to mix with the cool liquidentering the evaporator, warming it. The warmer liquid requires lessheat energy to vaporize and does not absorb as much heat from the airflowing over the evaporative surface or from the water condensingthereon. Thus, water on the evaporative surface is not cooled to thefreezing point and no ice forms. When the temperature sensor sends asignal to the controller that is at or above the high temperature setpoint, the controller causes the hot gas bypass to close. Thus, the hotgas bypass can provide precise control, within fractions of a degree F.,of the temperature of the liquid flowing through the evaporator and,therefore, of the evaporator surface and of water condensing on thatsurface. The temperature of the water on the evaporative surface can bemaintained at a temperature barely above freezing without ice formationwhich results in maximum efficiency both in terms of extracting as muchwater as possible from the ambient air in contact with the evaporativesurface and avoidance of down-time due to evaporator freezing.

[0085] The hot gas bypass of this invention may comprise a unit with asingle inlet and a single outlet, in which case the outlet is usuallyoperatively coupled to the outlet of the metering means (or the inlet ofthe evaporator, which, practically speaking is the same as the outlet ofthe metering means since, as can be seen in FIG. 1, the outlet of themetering means is coupled to the inlet of the evaporator). However, itis within the scope of this invention that the hot gas bypass comprisesa manifold having one inlet coupled to the outlet of the compressor anda plurality of outlets coupled to inlets at various points on theevaporative surface. Such an arrangement would generally and mostadvantageously be used in conjunction with a plurality of ice formationsensors, likewise located at various points on the evaporative surface.The inlets from the hot gas bypass manifold could be located at anydesired distance upstream, i.e., in the direction counter to the flow ofrefrigerant in the system, from the sensors. When a sensor senses alocal formation of ice, it would send a signal to the controller whichin turn would send a signal to the manifold to open, without limitation,a solenoid operated valve upstream from that sensor. In this manner,precise, local control of the temperature of the evaporative surfacewould be possible. This latter device and procedure would beparticularly useful when very large evaporative surfaces are being used.

[0086] The above described device of this invention will accomplish thepurpose of this invention, i.e., operate in a refrigeration cycle whileavoiding evaporator icing, at virtually any temperature, however, it isparticularly effective under extreme conditions, i.e., ambient airtemperatures below 55° F., even below 32° F. It would also beparticularly useful during very long periods of continuous operation. Attemperatures above about 55° F.; however, a device of this invention mayfurther comprise, as the metering means, a thermal expansion valve (TXV)that is controlled by a temperature-sensing bulb assembly. A TXV canalso control the temperature of liquid entering an evaporator but doesso by controlling the amount of liquid that reaches the evaporator atany given time rather than by injecting hot gas into the liquid streamentering the evaporator. Thus, under less extreme conditions, that is,at temperatures above about 55° F., a TXV can reduce some of thework-load on the hot gas bypass by providing an additional degree ofcontrol of the temperature of liquid entering the evaporator. TXVs arewell-known in the art as are the temperature sensing bulbs that controlthem. However, the temperature-sensing assembly described herein, whichprovides a degree of TXV control precision consummate with a device ofthis invention, i.e., that allows operation of the device without icingof the evaporative surface, is novel.

[0087] The temperature-sensing assembly comprises a thermal well inwhich a standard temperature-sensing bulb is placed, the thermal wellbeing constructed so as to rapidly transmit small changes in thetemperature of the gas exiting the evaporator outlet to thetemperature-sensing bulb which can then precisely control the operationof the TXV. To accomplish this, the thermal well has a baffled annularspace through which the liquid refrigerant passes before entering theevaporator. The baffle increases the residence time in the annular spaceto ensure that temperature changes in the liquid refrigerant aretransmitted to the wall of the thermal well. The space between thetemperature-sensing bulb and the wall of the thermal well is filled witha highly thermoconductive material that efficiently and rapidlytransmits changes in refrigerant liquid temperature from the wall of thethermal well to the temperature-sensing bulb.

[0088] A device of this invention may also comprise one or more frostsensors at various points on the exterior surface of the evaporator asan added icing deterrent during extreme temperature or prolongedcontinuous operation conditions. Frost detectors, which are capable ofdetecting the initial formation of ice on a surface, are well-known inthe art and would be used without modification with a device of thisinvention. However, rather than operate in the normal fashion ofconventional frost detectors and simply turn off the compressor if frostis detected, in the present invention, the frost detectors are incommunication with the controller. When the controller receives a signalfrom the frost sensor that ice is beginning to form in the vicinity ofthat sensor, it sends a signal to open the hot gas bypass. The hot gasbypass might be programmed to remain open for a brief predeterminedperiod of time during which a small charge of hot gas is injected intothe liquid entering the evaporator. These bursts of hot gas wouldcontinue until the frost sensor stops sending a frost signal. In thealternative, once the open signal has been sent to the hot gas bypass,the hot gas bypass remains open until the frost detector stops sending asignal to the controller, indicating that ice is no longer beingdetected, at which time the controller sends a close signal to the hotgas bypass.

[0089] Another device for the detection of ice formation would be one ormore lasers. The laser would monitor the surface of the evaporator andalert the controller when ice, virtually at the mono-molecular thicknesslevel, was beginning to form on the evaporator. This could beaccomplished, without limitation, by using the laser to detect minutechanges in the distance between the laser and the evaporative surface,i.e., by thickness measurement. It could also be accomplished bydetecting changes in the wavelength of light being emitted by the laserdue to its passing through a forming layer of ice. Other ways to use alaser will become apparent to those skilled in the art based on thedisclosures herein; all such approaches are within the scope of thisinvention.

[0090] An alternative or, if desired, concurrent means for preventingice formation on the evaporator, which would be particularly useful whenthe use to which the device herein is being put is the maintenance ofthe air temperature in a room or chamber at below the freezing point ofwater; i.e., lower than 32° F., would be to employ a temperature sensorthat detects the temperature of a surface of a work-load temperaturesensitive sub-assembly of the device. By “sub-assembly” is meant,without limitation, any discrete portion of the device such as thecondenser, the evaporator, the compressor, the metering means, etc. By“work-load temperature sensitive” is meant that, as the amount of workthat the sub-assembly must do to maintain the temperature in the room orchamber at the selected sub-freezing temperature increases, thetemperature of a surface, usually the outer surface, of the sub-assemblyrises. The sensor would be attached to surface of the sub-assembly and,during the initial operation of the device, would continuously detectits temperature and transmit the temperature to the controller. Thecontroller would then recognize that temperature, which, since it wouldbe generated during the early stage of operation of the device duringwhich ice would not have time to form, as the “normal operatingtemperature” of the subassembly. Since the normal operating temperaturewould not likely be absolutely stable even during normal operation, thecontroller could be programmed to establish a temperature range based onthe transmitted temperature, which would then be the “normal operatingtemperature range.” During operation of the device, the sensor wouldcontinuously detect and transmit to the controller the temperature ofthe surface of the sub-assembly. When the controller receives atemperature signal that is outside, usually above, the normal operatingtemperature range, the controller would cause the hot gas bypass to openbriefly which would result in a burst of hot gas to mix with the coolliquid entering the evaporator warming it and thereby melting any icethat was beginning to form on the evaporative surface. In thealternative, the controller could cause the hot gas bypass to open andremain open until the controller receives a signal that is within thenormal operating temperature range at which time the controller wouldsend a close signal to the hot gas bypass. An example, withoutlimitation, of a work-load temperature sensitive sub-assembly of thedevice herein would be the compressor. As the compressor works harder tomaintain a desired room or chamber temperature, the case of thecompressor will warm slightly. This increase in case temperature wouldbe detected by the sensor and transmitted to the controller which wouldinterpret the signal as an indication that that the device was workingharder due to the formation of ice on the evaporative surface. Thecontroller would then send an open signal to the hot gas bypass, causinga release of hot gas from the hot gas bypass. Another sub-assembly thatcould be used to detect initial ice formation would be the motor of thefan than circulates air over the evaporative surface. As ice begins toform on the evaporative surface, air being blown over and in contactwith the surface would come in contact with the ice, which is at 32° F.,instead and not the surface, which would be at a at a sub-freezingtemperature. The fan would then have to stay on longer and work harderto try to get the temperature of the air to the desired lowertemperature and, as a result, the temperature of the fan motor willrise. When the controller received a temperature reading from a sensorattached to the surface of the motor that is above the “normal operatingtemperature” of the motor, the controller again causes the hot gasby-pass to open. Other sub-assemblies that are work-load temperaturesensitive will be apparent to those skilled in the art. Any of these canbe used in the above manner to control the formation of ice on theevaporative surface; all such sub-assemblies are within the scope ofthis invention.

[0091] The device of this invention may also comprise a plurality ofevaporators. The evaporators may be connected in parallel off of amanifold, which in turn may be connected to the outlet of the meteringmeans, the outlet of the condenser or the outlet of the compressor. Ineach of these cases, the requisite additional elements of the devicewould be connected to the manifold. That is, for example, if themanifold is connected to the outlet of the compressor, then a condenserand a metering means would be included between the manifold and eachevaporator. Each evaporator can then be connected to its own hot gasbypass, its own temperature sensor and controller and, optionally, itsown TXV and temperature-sensing assembly. Or a plurality of evaporatorsmay be connected to a manifold which, in turn, is connected to a singlehot gas bypass/temperature sensor/controller/TXV/temperature-sensingassembly.

[0092]FIG. 2 schematically depicts a device of this invention. Thedevice comprises a compressor 10 that compresses a refrigerant gas,heating it in the process, and delivers the compressed hot refrigerantgas to condenser 20. Condenser 20 receives the hot refrigerant gas andcondenses it to a warm liquid refrigerant meanwhile transferring theheat of condensation to air flowing over and in contact with the surfaceof condenser 20, for example, in the direction of arrow 15. A capillarytube 30 receives the hot liquid refrigerant and expands the same to aliquid of reduced temperature and pressure. At this point, some of thereduced temperature liquid may already be converted to a gas so that, infact, the fluid at the outlet of the capillary tube 30 is a mixture ofliquid and gas. However, for the purposes of the refrigeration cyclethat the liquid/gas is undergoing, it is the liquid that is important.The cool liquid refrigerant next passes into and through evaporator 40wherein it exchanges thermal energy with the inner surface of evaporator40, the outer surface of which is in contact with external circulatingair. That is, the cool refrigerant liquid absorbs heat from thecirculating air through the surface of evaporator 40. As the result ofthe absorption of heat, the cool refrigerant liquid vaporized to a coolrefrigerant gas. The temperature of the cool refrigerant gas isessentially the same as that of the liquid from which it was generated,the energy absorbed being the heat of vaporization. The cool gas thentravels to compressor 10 and the cycle begins anew. The circulation ofthe refrigerant from compressor 10 to condenser 20 to capillary 30 toevaporator 40 and back to compressor 10 is called the refrigerationcycle. The refrigeration cycle, however, may also be thought of as awater removal cycle if the air circulating over evaporator 40 containswater vapor and if the temperature of the air is reduced to below itsdew point so that water condenses on the outer surface of theevaporator. In one embodiment of the present invention, the coolrefrigerant liquid flowing through evaporator 40 is in fact maintainedat a temperature that is below the dew point of external ambient air incontact with the evaporative surface so that, if the air contains watervapor, that water vapor will condense on the surface. The water thenwill gravity-flow off the evaporative surface and either be discarded,if air drying is the use to which the device is being put, or into acontainer if production of potable water is the purpose of the device.

[0093] In order for the device of FIG. 2 to operate without ice build-upon the evaporative surface, the device includes a hot gas bypassassembly. That is, thermocouple 50, which is coupled to the outersurface of the line at or near the inlet 42 of evaporator 40, derivesthe temperature of the cool liquid entering evaporator 40 from thetemperature of the line and sends a signal corresponding to thattemperature to microprocessor 60. Microprocessor 60 is programmed with afirst and a second set point temperature. The first set pointtemperature is a low set point temperature and the second set pointtemperature is a high set point temperature. The set point temperaturesare calculated as the temperatures that will maintain the liquidentering evaporator 40 at a desired temperature, which, in a presentlypreferred embodiment hereof, is between 32.5° F. and 33° F. The actualvalue of the set point temperatures will vary based on the thermodynamiccharacteristics of the material used in the manufacture of the line andto the sensitivity of the thermocouple. For example, without limitation,if the line is made of copper, which is highly thermoconductive, the setpoint temperatures are set close to the desired liquid temperature. Onthe other hand, if the line is made of steel, which is lessthermoconductive, the temperatures must be set so as to allow for thelag time in temperature change at the outer surface of the line comparedto that of the liquid in the line. Determination of appropriate high andlow temperature set points is essentially empirical but is well withinthe capability of those skilled in the art based on the disclosuresherein.

[0094] When microprocessor 60 receives a temperature signal fromthermocouple 50 that is at or below the low set point temperature,microprocessor 60 sends a signal to solenoid 75 which is then activated.When activated, solenoid 75 causes hot gas bypass valve 70 to open. Whenhot gas bypass valve 70 opens, hot gas from the outlet side 72 ofcompressor 10 is delivered to the inlet side 42 of evaporator 40 whereit mixes with the cool liquid, possibly containing some cool gas, andwarms the liquid. When the temperature signal received by microprocessor60 is at or above the second, high temperature set point, themicroprocessor stops sending a signal to solenoid 75, which thendeactivates, allowing hot gas bypass valve 70 to close. In this manner,the temperature of the liquid entering evaporator 40 is preciselycontrolled.

[0095] Rather than a simple capillary tube, the metering means may alsobe a TXV as shown in FIG. 3. If so, the amount of hot liquid refrigerantbeing expanded by TXV 33 is controlled by temperature sensing bulb 35,which is situated in thermal well 38 (FIG. 4). In a presently preferredembodiment of this invention, the thermal well/temperature-sensing bulbis located at the outlet from the evaporator. However, the thermalwell/temperature-sensing bulb may be located at other positions such asat the inlet of the evaporator also. Thermal well 38 is, for example,without limitation, a double-walled cylinder having walls 100 and 101and space 110 between them. Space 110 contains a baffle or series ofseparate baffles 120 that run throughout space 110. Thermal well 38 alsohas an inlet 112 to space 110 and an outlet 113 from space 110. Thetemperature in thermal well 38 is derived from the temperature of thecool refrigerant liquid at the inlet to evaporator 40. This isaccomplished by diverting the cool refrigerant liquid before it entersevaporator 40 into inlet 112 through space 110 wherein it is flowsaround baffle 120, which results in it being in contact with inner wall101 for a sufficient period of time for inner wall to be cooled to thesame temperature as the liquid, and then out through outlet 113 and intoevaporator 40. In this manner also, the liquid is in contact with innerwall 101 for a sufficient time that the temperature of inner wall 101will change to reflect changes in the temperature of the liquid.Temperature-sensing bulb 35 is surrounded by thermal compound 130, whichis a substance that rapidly and efficiently conducts heat so thatchanges in temperature at inner wall 101 are rapidly and efficientlytransmitted to temperature-sensing bulb 35. Examples of such substancesare, for example and without limitation, phase change thermal compounds(PCTC) such as Chromerics T725, MPU 3/7 Aluminum Oxide or Arctic Silver.Temperature-sensing bulb 35 contains a gas such as, without limitation,a Type “C” gas, the pressure exerted by which is extremely temperaturesensitive. Thus, as the temperature in thermal well 38 decreases due toa decrease in the temperature of the gas at the inlet to the evaporator40, the pressure in sensing bulb 35 decreases. As the pressuredecreases, a spring (not shown) in TXV 33, which has been compressed dueto pressure being placed on it by the gas in sensing bulb 35, pushesagainst and closes a diaphragm (not shown) in TXV 33, which results in arestriction in the flow of refrigerant through TXV 33. TXVs, sensingbulbs and their operation are well known to those skilled in the art.The use, however, of baffled thermal well 38 and thermal compound 130 toobtain rapid transfer of small temperature changes from the coolrefrigerant liquid to sensing bulb 35, is novel and is a part of thisinvention.

[0096] The TXV/temperature-sensing bulb/thermal well of this inventioneffectively prevents icing of evaporator 40 at ambient air temperaturesabove about 55° F. However, as air temperature goes below about 550° F.,the TXV/temperature-sensing bulb/thermal well system is not capable ofcontrolling the temperature of the liquid on the input side of theevaporator enough to stop icing of the evaporative surface. Thus, attemperatures below about 55° F., the hot gas bypass of this inventioncomes into play. Thermocouple 50, which is coupled to the outer surfaceof the line connecting TXV 33 with evaporator 40, derives thetemperature of the cool liquid entering evaporator 40 from thetemperature of the line and sends a signal corresponding to thattemperature to microprocessor 60. Microprocessor 60 is programmed with afirst and a second set point temperature. The first set pointtemperature is a low set point temperature and the second set pointtemperature is a high set point temperature. The set point temperaturesare calculated as the temperatures that will maintain the liquidentering evaporator 40 at a desired temperature, just as they are whenthe metering means is a capillary, described above. Thus, in a presentlypreferred embodiment of this invention, it is desirable to maintain thetemperature of the refrigerant liquid entering the evaporator at between32.5° F. and 33° F. and the set point temperatures are set accordingly.However, if a device of this invention is to be used in a freezer wherethe goal is to cool ambient air to below 32.5° F., then the temperatureof the refrigerant liquid must be substantially colder and the set pointtemperatures are set such as to maintain that colder temperature. Thus,the values of the set point temperatures will depend on the use to whichthe device is being put and the determination of those temperatures willbe well within the capability of those skilled in the art based on thedisclosures herein.

[0097] When microprocessor 60 receives a temperature signal fromthermocouple 50 that is at or below the low set point temperature,microprocessor 60 sends a signal to solenoid 75 which is then activated.When activated, solenoid 75 causes hot gas bypass valve 70 to open. Whenhot gas bypass valve 70 opens, hot gas from the outlet side 72 ofcompressor 10 is delivered to the outlet side 74 of TXV 33 where itmixes with the cool liquid, possibly containing some cool gas, and warmsthe liquid. When the temperature signal received by microprocessor 60 isat or above the second, high temperature set point, the microprocessorstops sending a signal to solenoid 75, which then deactivates, allowinghot gas bypass valve 70 to close. In this manner, the temperature of theliquid entering evaporator 40 is precisely controlled.

[0098] A device of this invention may comprise a hot gas bypass manifoldand a plurality of ice formation sensors. This is shown in the schematicof FIG. 5. In FIG. 5, multiple ice formation sensors 240 monitorevaporative surface 290 for the formation of ice. Monitoring points 240may comprise sensors coupled directly to the evaporative surface, suchas in the case of temperature sensors or frost sensors, or they maymonitor the surface in a remote fashion as in the case of a laser beamdirected at the surface. In any event, the signal from the sensors maybe collected at bus 210 through connection 250 or they may be sentdirectly to a controller 200. Connections 250 may, without limitation,be hard wired or they may comprise radio signal connections. They aredepicted in FIG. 5 as wires for ease of understanding only. Whencontroller 200 receives a signal from one or more of sensors 240, itsends a signal to hot gas bypass manifold 220. Manifold 220 has an inlet270 that is connected to the outlet of a compressor (not shown). Thus,manifold 220 contains hot gas from the outlet of the compressor. Whenthe manifold receives a signal from controller 200, the appropriate lineor lines 260 is/are opened so that hot gas may enter evaporative surface290 at one or more of inlets 230. The opening and closing of the linesis controlled by, without limitation, solenoid activated valves. Othermeans of controlling the opening and closing of the lines will becomeapparent to those skilled in the art based on the disclosures herein andare within the scope of this invention. Inlets 230 are located at anoptional distance upstream, that is in direction counter to the flow ofrefrigerant through the system (i.e., refrigerant enters the evaporatorat 285 and exists at 280) from ice formation sensors 240. Thus, hot gaswill enter the evaporator at 230 and mix with the refrigerant liquidtherein resulting in warming of the evaporative surface in thedownstream direction. Lines 260 will remain open until controller 200ceases to receive a signal from sensors 240 or, when the sensors aretemperature sensors, until controller 200 receives a signal from sensorsindicating that a selected second set point temperature (the first setpoint temperature being a low temperature indicating icing) has beenreached. At such time, controller 200 sends a signal to hot gas bypassmanifold 220 to close lines 260 so that no more hot gas will pass toinlets 230 to mix with the refrigerant. In this manner, very precisecontrol of the formation of ice on the evaporative surface can beachieved.

[0099] If desired, a receiver (not shown) may be included in the lineconnecting condenser 20 and TXV 30. The received acts as a reservoir,holding the warm, high pressure refrigerant liquid until it is needed bythe metering device.

[0100] In another example seen in FIG. 6, which shows an embodimetn ofthe invention used on freezer. In this embodiment, the microprocessormay receive a signal from a timer 300. When microprocessor 60 receives atime signal from the timer 300, the microprocessor 60 sends a signal tosolenoid 75 which is then activated. When activated, solenoid 75 causeshot gas bypass valve 70 to open. When hot gas bypass valve 70 opens, hotgas from the outlet side 72 of compressor 10 is delivered to the outletside 74 of TXV 33 where it mixes with the cool liquid, possiblycontaining some cool gas, and warms the liquid. When the set end timehas been reached, the timer 300 signals the microprocessor to signalsolenoid 75, which then deactivates, allowing hot gas bypass valve 70 toclose. In this manner, the temperature of the liquid entering evaporator40 may befarily precisely controlled. The period between cycles and thelength of each cycle may be pre-set or dynamically adjusted based on thecircumstances under which the device is opertaing at a given time.

[0101] In other embodiments, the microprocessor 60 may receive signalsfrom more than one signal source. For example, FIG. 6 also includes atemperature sensor or temperature sensing means 310 and an ice detectoror ice detection means 320, in addition to the timer already discussed.In alternate embodimetns, only one sensor the temperature sensor 310 orthe ice detector 320) rather than both may be included. The signalcausing the controller 200 to activate the hot gas bypass may bedifferent than the signal that causes the controller 200 to de-activatethe hot gas bypass. The table below discloses possible cobinations.Signal source causing Signal source causing activation of hot gasbypass. de-activation of hot gas bypass. Time Time TemperatureTemperature Ice detection Ice detection Time Ice detection TemperatureTime Ice detection Temperature Time Temperature Temperature Icedetection Ice detection Time

[0102] As can be seen from the table, in embodiments of the inventionincluding more than one signal source, each signal source may beresponsible for causing the controller to act. For example, embodimentof the invention may include the use of a signal from one or more of atimer means, a temperature sensing means, and a ice detection means tobe received by the controller, causing the controller to activate thehot gas bypass. And, then use a signal from one or more of a timer, atemperature sensing means, and/or an ice detection means to be receivedby the controller, causing the controller to deactivate the hot gasbypass. In some embodiments, one signal source may be responsible onlyfor causing the controller to activate the hot bypass means, and anothersignal source is responsible only for causing the controller todeactivate the hot gas bypass mean. In other embodiments, the signalsources may be used for either purpose.

[0103] When a device of the present invention is used to produce potablewater, a container is placed underneath the evaporator to collect waterflowing off it. The container is either made of a non-contaminatingmaterial such as, without limitation, Teflon®, PVC, nylon and othersynthetic polymers, stainless steel, glass and the like or is lined orcoated with such a material. A presently preferred material for coatingall elements that come in contact with water is an enamel material knownas FDA Gray. The container may simply be placed under the evaporator orit may be detachably fitted to the lower portion of the evaporator togive a compact portable unit. In addition, the container may be fittedwith a fritted glass gas dispersing element which is connected to anelectrostatic ozone generator so that ozone can be bubbled through thecollected water to inhibit the growth of microorganisms and maintain thepurity of the water. A device of this invention used for the collectionof potable water also may include one or more filters such as a carbonblock, a limestone of a sediment filter to further assure the potabilityof the collected water.

[0104] Thus, it will be appreciated that the present invention providesa device and method for preventing icing of the evaporative surface ofan evaporator during operation of a refrigeration cycle. Althoughcertain embodiments and examples have been used to describe the presentinvention, it will be apparent to those skilled in the art based on thedisclosures herein that changes in the embodiments and examples shownmay be made without departing from the scope of this invention. Otherembodiments are within the following claims.

What is claimed:
 1. A device, comprising: a compressor comprising aninlet and an outlet, a condenser, comprising an inlet and an outlet,wherein the condenser inlet is operatively coupled to the outlet of thecompressor, a metering means, comprising an inlet and an outlet, whereinthe inlet of the metering means is operatively coupled to the outlet ofthe condenser, an evaporator, comprising an inlet, an outlet and anevaporative surface, wherein the evaporator inlet is operatively coupledto the outlet of the metering means and the outlet of the evaporator isoperatively coupled to the inlet of the compressor, a hot gas bypasssystem, comprising an inlet, an outlet, an open position and a closedposition, wherein the inlet is operatively coupled to the outlet of thecompressor and the outlet is operatively coupled to the inlet of theevaporator or to an inlet of a manifold. a refrigerant that circulatesfrom the compressor to the condenser to the metering means to theevaporator and back to the compressor in a refrigeration cycle, acontroller operatively coupled to the hot gas bypass system, and a timeroperatively coupled to the controller.
 2. The device of claim 1 furthercomprising one or more ice detection means operatively communicatingwith the controller.
 3. The device of claim 1 further comprising atleast one temperature sensing means operatively in communication withthe controller.
 4. The device of claim 2 further comprising at least onetemperature sensing means operatively in communication with thecontroller.
 5. The device of claim 1 wherein the manifold comprises aninlet and a plurality of outlets, each outlet being operatively coupledto a different one of a plurality of inlets at different locations onthe evaporative surface,
 6. A method for performing a refrigerationcycle without ice build-up on the evaporative surface, comprising:providing a compressor comprising an inlet and an outlet; providing acondenser, comprising an inlet and an outlet, wherein the condenserinlet is operatively coupled to the outlet of the compressor; providinga metering means, comprising an inlet and an outlet, wherein the inletof the metering means is operatively coupled to the outlet of thecondenser; providing an evaporator, comprising an inlet, an outlet andan evaporative surface, wherein the evaporator inlet is operativelycoupled to the outlet of the metering means and the outlet of theevaporator is operatively coupled to the inlet of the compressor;providing a hot gas bypass system, comprising an inlet, an outlet, anopen position and a closed position, wherein the hot gas bypass meansinlet is operatively coupled to the outlet of the compressor and the hotgas bypass means outlet is operatively coupled to the inlet of theevaporator or to an inlet of a manifold, providing a controller capableof actuating the hot gas bypasssystem; a timer capable of sending asignal to the controller; and providing a refrigerant that circulatesfrom the compressor to the condenser to the metering means to theevaporator and back to the compressor in a refrigeration cycle.Providing a timer capable of sending a signal to the controller.
 7. Themethod of claim 6 further comprising the step of causing the timer tosend a signal to the controller causing the controller to alternatelyactivate and deactivate the hot gas bypass system
 8. The method of claim6 further comprising the step: providing a temperature sending means. 9.The method of claim 8 further comprising the step: causing the timer tosend a signal to the controller causing the controller to activate thegas bypass system.
 10. The method of claim 9 further comprising thestep: causing the temperature sending means to send a signal to thecontroller causing the controller to deactivate the gas bypass system.11. The method of claim 8 further comprising the step: causing thetemperature sensing means to send a signal to the controller causing thecontroller to activate the gas bypass system.
 12. The method of claim 11further comprising the step: causing the timer to send a signal to thecontroller causing the controller to deactivate the gas bypass system.13. The method of claim 6 further comprising the step: providing an icedetection means.
 14. The method of claim 13 further comprising the step:causing the timer to send a signal to the controller causing thecontroller to activate the hot gas bypass system.
 15. The method ofclaim 9 further comprising the step: causing the ice detection means tosend a signal to the controller causing the controller to deactivate thehot gas bypass system.
 16. The method of claim 13 further comprising thestep: causing the ice detection means to send a signal to the controllercausing the controller to activate the hot gas bypass system.
 17. Themethod of claim 11 further comprising the step: causing the timer tosend a signal to the controller causing the controller to deactivate thegas bypass system.
 18. A method for performing a refrigeration cyclewithout ice build-up on the evaporative surface, comprising: providing acompressor comprising an inlet and an outlet; providing a condenser,comprising an inlet and an outlet, wherein the condenser inlet isoperatively coupled to the outlet of the compressor; providing ametering means, comprising an inlet and an outlet, wherein the inlet ofthe metering means is operatively coupled to the outlet of thecondenser; providing an evaporator, comprising an inlet, an outlet andan evaporative surface, wherein the evaporator inlet is operativelycoupled to the outlet of the metering means and the outlet of theevaporator is operatively coupled to the inlet of the compressor;providing a hot gas bypass, comprising an inlet, an outlet, an openposition and a closed position, wherein the hot gas bypass inlet isoperatively coupled to the outlet of the compressor and the hot gasbypass outlet is operatively coupled to the inlet of the evaporator orto an inlet of a manifold, wherein: the manifold comprises an inlet anda plurality of outlets, each outlet being operatively coupled to adifferent one of a plurality of inlets at different locations on theevaporative surface; providing a controller operatively coupled to thehot gas bypass; providing a refrigerant that circulates from thecompressor to the condenser to the metering means to the evaporator andback to the compressor in a refrigeration cycle; and providing a signalsource communicating with the controller.
 19. The method of claim 18wherein the signal source comprises at least one signal source selectedfrom the group consisting of: a timer means, a temperature sensingmeans, and a ice detection means.
 20. The method of claim 18 wherein thesignal source comprises at least two signal sources selected from thegroup consisting of: a timer means, a temperature sensing means, and aice detection means.
 21. The method of claim 19 further comprising thestep: causing at least one signal source to signal the controller toactivate the hot gas bypass.
 22. The method of claim 21 furthercomprising the step: causing at least one signal source to signal thecontroller to deactivate the hot gas bypass.
 23. The method of claim 19further comprising the step: causing a signal from at least one signalsource selected for the group comprising a timer means, a temperaturesensing means, and a ice detection means to be received by thecontroller, causing the controller to activate the hot gas bypass. 24.The method of claim 23 further comprising the step: causing a signalfrom at least one signal source selected for the group comprising atimer means, a temperature sensing means, and a ice detection means tobe received by the controller, causing the controller to deactivate thehot gas bypass.